1. Field of the Invention
The present invention relates generally to printing apparatus, and more particularly to a printing wheel which carries type formed of resilient material, such as rubber, on its periphery for printing indicia, symbols or the like on flat, irregular or uneven surfaces.
2. Description of the Prior Art
In connection with the manufacture of packaged goods, it is conventional to print information, such as date codes, names and the like, in ink on the packages as they are being conveyed at a high rate of speed. Such packages may be of metal, plastic, cardboard, glass and the like, which in many instances present uneven and irregular surfaces on which a printing impression is to be made.
The type conventionally used is relatively soft rubber such that the force of type imprint can determine the clarity of the print. If too forceful, the type distorts and produces an unclear print or smudge. Elongated type segments of rubber usually carry a number of letters or numbers in seriatim. If the surface to be imprinted is irregular, the segment must essentially conform to such irregularities or else some of the parts of the surface will not be imprinted while others will be smeared.
Various printing wheel devices and rubber type designs have heretofore been employed to make clear imprints, at high speeds, on irregular surfaces, certain of these being the subject of U.S. Pat. Nos. 3,071,071, 3,093,070, 3,230,880 and 3,327,624. Such devices in various respects rely on the yieldability of the type or type segment in an attempt to secure a fairly uniform imprinting force of all of the type elements on an irregular surface being imprinted. However, if the type segment is not sufficiently yieldable at a high point on the surface, undue force can occur causing a distorted or smeared imprint to be made.